ACI 364.17T-18

A review of published literature indicates that there is plenty of information regarding the pH of concrete as it relates to carbonation, embedded steel corrosion, alkali-silica reaction, and effects of mineral admixtures such as fly ash and silica fume. There are, however, only a few research papers published that are related to test methods to measure the pH of a concrete surface.

Portland cement and many other hydraulic-cement-based concretes are highly alkaline materials. Depending on the actual chemistry of the portland cement and amount of alkalis present, the pH of freshly placed concrete can vary from approximately 12 to over 13. The carbonation of concrete is known to lower the surface pH to a value in the vicinity of 9.